Process of producing at the cooking of cellulose and especially of sulphite cellulose a. waste liquor containing a high percentage of organic matters



atented' Feb. 3, 1931 UNITED STATES PATENT OFFICE GUS'I'AF EAG IPUND, OF STOC KHOLM, SWEDEN, ASSIGNOB TO .PATENT-A-KTIEBOLAGET 'GRONDAL-RAMEN, OF STOOKHOLM, SWEDEN, A LIMITED COMPANY PCESS PRODUCING AT THE COOKING OF CELLULOSE AND ESPECIALLY OF SUL- PHI'IE CELLULOSE A WASTE LIQUOR CONTAINING A HIGH PERCENTAGE OF ORGANIC MATTERS E Drawing. Application filed larch 1, 1930, Serial No. 432,564, and in Sweden April At the cooking of cellulose it has been suggested to add to the cooking liquorpart of the waste liquor from a previous cooking operation for obtainin in that way a waste liquor containing a argc percentage of organic matters; by that treatment the materials dissolved in the liquors will be essentially more concentrated than liquors, consisting only of raw material dissolved in a watery solution. In the same manner such a concentration of organic matters in the waste li uor from a cooking operation can be obtaine by transferring to the fresh cooking liquor, destined for a new cooking operation, part of the liquor contained in a cooking apparatus alread in operation.

In these two cases the cooking, however, does not'ta-ke place in completely the same manner as when a water solution of the cooking means is used wit out any additlon of liquor from a revious cooking operation or operations. n the case last mentioned the cooking process takes lace more slowly and the product may easlly obtain a dar colour and also will become weakened on account of the extension of the cooking period. The present invention has for its obyect to prevent these inconveniences whether .the' coohng liquor has been mixed with cooking liquor from previous cookings or wlth 11 nor from such one still under action. Accor mg to my invention the wooden chip before the cooking operation is brought to absorb the ccog liquor, prepared in the usual manner with water and that thereupon waste liquor from a previous cooking operation or from a cooking apparatus, the contents of which is still under cooking, is added.

The process is carried out 1n such a manher, that a cooking liquor, containing ases or not, which has not before been use for cooking, is fed into 'acooking apparatus, con taining wooden chips, which will then absorb part of the li nor, the rest of which is thereupon drawn cm the fzirpparatus. That apparatus is thereafter led with a cooking liquor consisting of a mixture of the same liquor as that above stated and awaste liquor from a previous pulp cookin process or a liquor from such process, stl not finished.

' HEISSUED The cooking operation in the apparatus thus charged is thereupon begun. This treatment will not cause any loss of time, because the chips in all circumstances want some time for the absorbation of the cooking liquor. The process requires, however, an increased pump ing action. For effecting a rapid sucking in of the unmixed cookingcliquor in the chips. the cooking apparatus, as stated, is com pletcly filled with that liquor.

The pumping means are arranged in such a manner that the liquor is introduced in the cooking apparatus under pressure, because it will hereby become possible to facilitate the saturation of the chips and thereby to shorten the time for the sucking operation. This saturation of the chips with cooking liquor before the cooking operation of course may take place outside the cooking vessel or apparatus itself and the cooking thereupon may be carried out in the latter one after its filling with fresh cooking liquor mixed with waste liquor from a previous cooking or with liquor from a cooking apparatus in operation as mfintioned at the end of the first paragra 1 e impregnation of the chips with cooking liquor before the cooking process roper, as stated above, is of importance for t e said process at every cooking of cellulose and must take place so substantially and rapidly as possible, for which reason the use of pressure at the soaking is of cat importance also for the cooking operatlons used at present. Such a soaking of the chips with unmixed cooking liquors before the cooking operation but with that o eration executed b mixed cooking liquor o the composition, above stated, is of the same importance for other processes of cellulose cooking, for instance by alkaline cooking 0 rations, even althou h the inconveniences t ereb are not so evi cut as in the production of sul phite cellulose.

Having now particularly described the nature of my invention and the manner of its operation, what I claim is:

1. An improved rocess of producing at the cooking of cell ose, for instance of sulphite cellulose waste liquors, containing a high percentage of organic matters, characterized thereby, that the chips, before the cooking are soaked with a cooking liquor, produced in the usual manner Without any ecldition of Waste liquors from previous cooking operations, and that after an eventual removal of part of the cooking liquor, the cook ing is executed with a cooking liquor, mixed with Waste liquor from a previous cooking or with such liquor from a cooking apparatus, still in action.

2. The process statei in the claim 1, characterized thereby, that the soaking of the chips with cooking liquor before the cooking operation is carriedl out unoler pressure, for the purpose of facilitating the soaking.

GUSTAF HAGLUND.

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